Silver halide emulsions containing coupler solvents

ABSTRACT

A method of obtaining color records of improved heat stability, also novel photographic emulsions and elements characterized by using one or more aliphatic or trimellitic- or trimethyl 1,3 pentane-diol diesters, or corresponding polyesters, as permanent coupler solvents.

United States Patent [1 1 McCrossen et al.

[ Dec. 18, 1973 SILVER HALIDE EMULSIONS CONTAINING COUPLER SOLVENTS Inventors: Fred C. McCrossen; Harland J.

Osborn, both of Rochester, N.Y.

Assignee: Eastman Kodak Company,

Rochester, NY.

Filedz' Aug. 31, 1972 Appl. No.: 285,288

US. Cl 96/56.5, 96/55, 96/56,

96/74, 96/100 Int. Cl G03c 7/00, G03c 1/40 Field of Search 96/56.5, 55, 100

References Cited UNITED STATES PATENTS 11/1966 Kainrath et a1. 96/100 3,409,439 1 H1968 Yoshida et a1 96/100 3,413,123 11/1968 Nittel et a1 96/100 3,554,755 l/l971 Rinauro 96/100 3,676,141 7/1972 Hara et al. 96/100 Primary Examiner-J. Travis Brown Attorney-Robert W. Hampton et a1.

[5 7] ABSTRACT 29 Claims, No Drawings 1 2 SILVER I-IALIDE EMULSIONS CONTAINING activity with oxidized developing agents, there is a con- COUPLER SOLVENTS tinuing need for more efficient solvent systems and techniques for utilizing couplers in general color photo- This invention relates to color photography and pargraphic systems.

ticularly to improved color photographic elements and 5 It is an object of the present'inventionto improve the a method for efficiently incorporating substantially efficiency and stability of coupler dispersions within non-diffusible color couplers into one or more silver photographic silver halide emulsions and also to imhalide emulsion layers or a color photographic element prove the heat stability of the photogra'p hic record obto obtain photographic dyes of improved stability. tained when the dispersed couplers are reacted with ox- Color photographic elements containing hydrophoidized color developing agents andprocessed.

bic dye-forming couplers dispersed in one or more light These and other objects are obtained by utilizing in sensitive emulsion layers are well known in the art. the usual manner as permanent coupler solvent one or Generally speaking, such elements contain a support more esters of the group:

and aplurality of sensitized silver halide gelatin emulsion layers such as red-, greenand blue-sensitive emul- (A) sions applied thereto; each of said emulsion layers, in r r? Rm I turn, normally contain dispersed particles consisting of 0- cH,|i1c:H,d1H-R one or more dye-forming couplers wholly or partly dissolved in a permanenthigh boiling couplers solvent or encapsulated in a polymeric or wax-like material (ref.

(B) RVII H 0 French Patents 2,017,718, 1,555,663and U.S.Pat. No. A] V 2 772 163). (R )zCH OCH2CCGH(R)7;

In preparing such coupler-containing silver halide emulsions, itis customary to dissolve the coupler in 'a O=dJCH(R )z high boiling coupler solvent such as tricresyl phos- (D) H:0-R phate, then mill the coupler solution into an aqueous v v; gelatin solution with a surfactant and, thereafter, comr, V bine the resulting dispersion with a light-sensitive R gelatino-silver halide emulsion. For such purpose, the 5 ratio of coup1er-to solvent can usefully vary from about 0.5l:23 (ref. .lelley U.S. Pat. Nos. 2,322,027 and (E) ,c vr 2,801,171). The true solubility of most color-forming couplers, however, is considerably lower than sug- Ha gested by the above ratio. In some cases, the solubility e of the coupler is in the area of about one part couplerto-ten parts of coupler solvent. As a result, the disherein persed droplets of coupler solution in the emulsion R m RIV and are individually defined at layer are supersaturated. Despite this fact, the presence eac Occurrence as a hydrogen atom or a lower alkyl of even aminimal amount of coupler solvent is considgr p. Pa cularly an alkyl of one to eight carbon ered a disadvantage for general color photographic to Such sm t yl. YL P PY 0r y purposes. Emulsion layers thickened by coupler sol- R" is defined as an arylcarbonyl group such as a phevents tend to be less durable and image resolution of nylcarbonyl or a naphthylcarbonyl group, or an alkylpoorer quality. For this reason, continuing efforts are c nyl group of two to 13 carbon atoms such as mebeing made to cut down on the amount of solvent withhylcarbonyl and dodecylcarbony out corresponding loss in coupler reactivity or dye stais defined as an alkoxy carbonyl group having up bility. For example, known high boiling crystalloidal I0 15 Carbon atoms, particularly two to 13 carbon coupler solvents have been used in combination with atoms u a methoxycarbonyl ordodecyloxycarboremovable auxiliary solvents to initially dissolve the y ,and n is an integer of 1-1000.

coupler (ref. Julian U.S. Pat. No. 2,949,360; Mannes Of particular interest as coupler solvents are esters of U.S. Pat. No. 2,304,939; .lelley et al. U.S. Pat. No. f fQl'mulae 2,322,827; Vittum U.S. Pat. No. 2,801,170; Fierke U.S. Pat. Nos. 2,801,171 and 2,490,749; Rinaura U.S. (F) 0 R Pat. No. 3,554,755, Thirtle et al. U.S. Pat. No. 11

t Rm

2,835,579; Sawdey U.S. Pat. No. 2,533,514 Improved 0 photographic emulsions of interest are generally surnl marized, for instance, in Section XXII, page 1 10, lines 1 1-50 of Product Licensing Index, Vol. 92, Publication 9232 (Dec., 1971). l j if Because of a marked difference in solubility among -o-cH1- CIIz- II-R the best known couplers, and variations in coupler rei in,

o on o 0 on 0 V 7 11 l 3 1 Ifl 11 (CHJ)ZCHC--OCHC-CHIO (cHi)i 0 CH- CHOCC1I(CH;)1

H CH: J H CH: 495a,, t e saw in which R and n are defined as above; permanent coupler solvents are defined as highboiling hydrophobic coupler solvents having a boiling point of about 175 C. which are permanently retained (H) i 10 as droplets dispersed within the silver halide emulsion (CH3)2CHCOCHEC$HCH(CHB)Z layer of a color photographic element. Permanent sol- CH; 0CCH(CH,); vents of particular interest are specifically described in the following table l-lV relating to formulae B-F supra.

(which is 2,2,4-trimethyl-l,B-pentanediol isobutyrate) l5 or a combination of one or more of the above com- 11! R1 pounds with a supplemental amount of one or more y other permanent high-boiling coupler solvents such as dibutyl phthalate, bis (2-ethylhexyl)phthalate, etc., ex- I emplified, for instance, in us. Pat. Nos. 2,322,027, I I

2,533,514, 2,801,171, 2,835,579 and 3,554,755.

For purposes of preparing a coating emulsion con- 0 R" taining one or more couplers it is also optional, though or convenient, to utilize one or more low boiling auxiliary solvents to aid in initially dissolving couplers. Suitable (B) i? i 3 auxiliary solvents of this type are described and exem- I plified, for instance, in US. Pat. Nos. 2,801,170, R"

2,801,171 and 2,949,360. g V O=dJ-CI[-(R )1 The above-defined permanent coupler solvents of this invention are generally available commercially TABLE 1 *(ref. Eastman Chemical Product Index; No. P143B; 14th Ed.( 1972); pg. 3) or otherwise obtainable by rec- Coupler ognized chemical steps, the (A) and (F) groups of 501- solvent R" R R R vents being synthesized, for instance, by refluxing an appropriate polycarboxybenzene or corresponding anhydride with an appropriate alcohol such as 2,2,4- trimethylpentanol, followed by concentration and recovery by molecular distillation.

Permanent solvents such as group (D), supra, are obtainable, for instance, by reacting pentaerithritol with methyllaurate in the presence of titanium butoxide as catalyst at a molar ratio of about I 1-4 with continuous removal of methanol-by-product.

obtainable by heating a reactive mixture of compounds such as 2,2,4 trimethyl 1,3 pentanediol with adipic acid 53 35:; n R at a molar ratio of about 2.2 d1ol-to-l.0 of the acid. In the presence of a catalyst such as titanium isopropoxide :3 2g g:a 23igaswith continuous removal of water, followed by the ad- 15 200 2: 2: 2: dition of about 1.1 mole of isobutyric acid. 16 000 3 i v 'o it 's under- 17 s C H H H For purposes of the present 11 ent1 n 1 I8 50 r H H stood that. 1 I I9 250 CHF CH" supplemental amount in reference to additional per- 20 850 CHi- CHi- C2H,-,- manent coupler solvents is intended to cover about 1 s. percent-67 percent (by volume) of the total amount of (D) CH,--0- -}1v permanent coupler solvent used in dissolving a coupler, 33 percent or less (by volume) being preferred; low- H2 boiling auxiliary solvent" is defined as an organic solor vent of either hydrophilic or hydrophobic type which (E) Hic-R has a low-boiling point within the range of about 65 to about C. and/or can be water washed from the silver halide emulsion and handled in the usual way; and Hi -R" litallast d non diffusible cyan dye-forming couplers suitable for use in the present invention are exemplified or suggested in U.S. Pat. Nos. 2,373,293; 2,423,730; 2,801,171; 2,895,826; 2,908,573; 3,046,- 129; 3,516,831; 3,311,476; 3,253,294; 3,458,315; 3,227,550; 3,476,563; 3,458,315; 3,419,390 and 3,034,892.

Useful non-diffusible magenta dye-forming couplers are exemplified or suggested, for instance, in U.S.

Pat. Nos. 2,600,788; 2,801,171; 2,983,608; 2,908;-

437; 3,152,896; 3,062,653; 3,006,759 and Belgian Patent 724,427.

csaes onain n"nearerfien-mngibifiaiow' dyeforming couplers are exemplified or suggested in U.S. Pat. Nos. 2,778,658; 2,875,057; 2,908,573; 3,227,550; 3,253,924; 3,227,155; 3,408,194; 3,447,; 928; 3,415,652; 3,384,657; 3,369,895; 3,265,506; and 3,227,554.

For purposes of the present invention, it is also found that DIR (Development Inhibitor Releasing) couplers can also be usefully included in the silver halide emulsion layers within the present invention. Compounds of this type are exemplified, for instance, in U.S. Pat. Nos. 3,227,554; 3,148,062 and in U.S.

Ser. No. 674,090, tied on Oct. 10, 1967.

An effective amount for non-diffusible couplers of the above type can range from about 5-200 mg/ft per emulsion layer of coated material, a concentration of l050 mg/ft' being generally satisfactory. Where DIR coupler is utilized in addition to 2- and/or 4- equivalent dye-forming couplers, it is found thatabout 5-30 mole percent of the former (i.e. DIR coupler) is adequate.

Color photographic elements within the scope of the present invention are preferably multilayered an usefully contain one or more of the following components:

A. A support layer as described, for instance, in Section X of Product Licensing Index, Vol. 92, Publication 9232 (Dec. 1971). Typical supports include cellulose acetate film, polystyrene film,

polyethylene film, polypropylene film, polyethylene terephthalate film, etc.

B. Red sensitive, a green sensitive and a blue sensitive silver halide emulsion as summarized, for instance, on page 107 (Section I and III) and pages 108-9 (Section XV) of Product Licensing Index, Vol. 92, Publication 9232 (Dec. 1971). Typical suitable silver halide emulsions include silver chloride, silver bromide, silver chlorobromide, silver bromoiodide, silver chlorobromoiodide, and silver chloroiodide-emulsions.

Usefully included in such emulsion layers are the usual addenda including an antistain agent such as described in U.S. Pat. No. 2,865,752.

C. One or more gelatin spacer layers can also be included between the light-sensitive emulsion layers and also a Carey-Lea filter layer; spacer layers of this type can optionally contain removable additives -to further improve dye stability and improve color separation and D. A protective gelatin overcoat layer.

The invention is further described although not limited by the following examples:

7 EXAM E- ,MHWMLH Fourteen light-sensitive gelatino silver halide emulsions identified as T1 through T-14 were prepared by dissolving 76 mg of 2-[a-(2,4-di-tert.-amyl- (phenoxy)-butyramido]-4,6-dichloro-5-methylphenol in an equal weight of different coupler solvents (or mixtures) identified respectively as di-n-butyl phthalate (T-1-3), tributyrin (T-4), trilaurin (T-5), di-

cyclohexyl phthalate (T-6), coupler solvents No. 21 (T-7), 25 (T-8), 29 (T-9), 1 (T-10), 3 (T 11), 15 (T-12), a mixture of solvent (Table V supra) No. 7

with bis (2-ethylhexyl) phthalate (66.6 percent 33.3

percent; T-l3); and a mixture of solvent No. 7 with bis(Z-ethylhexyl) phthalate (33.3 percent 66.6 percent: T-l4); solution of each coupler were obtained in the usual manner in the presence of 3ml of ethyl acetate as auxiliary solvent. Each coupler solution was then mixed with 36 ml of a 6 percent aqueous gelatin solution in the presence of a surfactant,

the emulsified material was chill set, water washed and dired to remove auxiliary solvent and the melted dispersioiiblended w i tli a light sensitive 'gel'afi' manner and loss in dye density reported in Table IV in terms of density units.

TABLE IV Emulsion Dens. Loss Coating No. Coup1er So1vent irmax Dmax Wet Dry T1-3 DNP 670 2.94 0.16 N 665 3.48 0.25 0.74 671 2.91 0.19 0.78 T-4 TB" 671 2.34 0.08 0.46 T-5 TL* 657 2.78 0.09 0.49 T-6 DCP 667 2.50 0.10 T-7 No. 21 667 1.91 0.06 0.30 T-8 No. 26 664 2.82 0.06 0.35 T-9 No. 29 658 2.86 0.08 0.39 T-10 No. 1 662 2.96 0.10 0.31 T-ll No. 3 661 2.76 0.08 0.34 T-12 No. 15 665 2.68 0.10 T-13 No. 7+BEP* 664 2.87 0.06

(66.6%:33.3%) T 14 No. 7+BEP* 665 2.87 0.09

* DNP Di-n-butyl phthalate TB tributyrin TL trilaurin DCP dicyclohexyl phthalate BEP bis-(2-ethylhexy1) phthalate not available (di-n-Butyl plithalate).

Developing Solution A 1.0 grams surfactant 4.0 grams Sodium sulfite 3.0 grams 4-amino-N,N-diethylaniline 20.0 grams Sodium carbonate 1.72 grams NaBr Water to 1.0 liter EXAMPLE [1 Four test emulsions identified as T-l5, T-l6, T-l7 and T-l 8 were prepared and tested as in Example 1 except that the incorporated couplers were the yellow dye-forming couplers (A) a-pivalyl-a-(4- carboxyphenoxy)-2-chloro-5-['y -(2,4-di-tert.- amylphenoxy butyramido]-acetanilide (ref. US. Pat. No. 3,408,194); and (B)a-pivalyl-a-[4-(4-benzyloxyphenylsulfonyl) phenoxy]-2-chloro-5-['y-(2,4-di-tert.- amylphenoxy) butyramido]-acetanilide (ref. US. Pat. No. 3,408,194). The coated test films were then exposed, developed and tested identically with Example 1 and the results recorded in Table V.

TABLE V Emulsion Dens. loss coating Cou- Coupler number pler solvent Max Dmnx. Wet Dry T-15 DNP 443 2. 75 17 12 T-16 (A) #7 (Table I). 444 2. 40 14 .05 T-17 NP 449 2. 90 26 27 T-18 (B) 446 2. 34 08 .10

u J +11 n (R02 whereiit R'"' and R"" are individually defined at each occurrence as a hydrogen atom or a lower alkyl group;

R" is defined as an arylcarbonyl group or an alkylcarbonyl group;

R" is defined as an alkoxy carbonyl group having up to carbon atoms and n is an integer of l-lOOO.

2. A method of claim 1 wherein the solvent system additionally contains a supplemental amount of a phthalic acid alkyl ester.

3. In a method for forming heat stable color photographic records obtained by exposing and developing a color photographic element containing one or more light sensitive silver halide emulsion layers having at least one photographic coupler,

the improvement comprising utilizing as permanent coupler solvent at least one compound of the formulae wherein R'-" are individually defined at each occurrence as a hydrogen atom, or an alkyl group of one to eight carbon atoms; and

R" is a phenyl carbonyl group or an alkyl carbonyl group of two to 13 carbon atoms.

4. ln a method for forming heat stable color photographic records obtained by exposing and developing a color photographic element containing one or more light sensitive silver halide emulsion layers having at least one photographic coupler,

the improvement comprising utilizing as permanent coupler solvent at least one compound of the formulae wherein R'-'-R" and R"" are individually defined at each occurrence as a hydrogen. atom or an alkyl group of one to eight carbon atoms; and n is an integer of 1-1000.

5. In a method for forming heat stableicolor photographic records obtained .by exposing and developing a color photographic element containing one or more light sensitive silver halide emulsion layers having at least one photographic coupler,

the improvement comprising utilizing as permanent coupler solvent at least one compound of the formula HzC-R RVI. vr

H2 vt wherein R is defined as an alkoxy carbonyl group of two to 15 carbon atoms.

6. A method of claim 1 wherein the permanent coupler solvent is a member selected from the group consisting of pentaerythritol tetrabenzoate; tetracarbethoxy propane; pentaerythritol tetralaurate; tris (2,2,4-trimethylpentyl) trimellitate; 1,2,4-benzenetricarboxylic acid, tris (2- ethylhexyl)ester; 2,2,4-

vtrimethyl-l,3-pentanediol isobutyrate, and a 2,2,4-

trimethylpentanediol-l,3-adipic acid polyester terminated with isobutyric acid.

7. A method of claim -1 wherein the solvent system contains leisopropyl-2,Z-dimethyltrimethylene-l ,3- diisobutyrate in a ratio of about 1 part by weight solvent-to-l part by weight coupler.

8. A light sensitive photographic silver halide emulsion having dispersed therein finely divided particles containing at least one color photographic coupler compound in a solvent system comprising at least one compound of the formulae II (R wherein R'" and'R" are individually defined ateach occurrence as a hydrogen atom or a lower alkyl group;

R" is defined as an arylcarbonyl group or an alkylcarbonyl group;

R is defined as an alkoxy carbonyl group having up to 15 carbon atoms and n is an integer of 1-1000.

9. A light sensitive photographic silver halide emulsion of claim 8 wherein the solvent system additionally contains a supplemental amount of a phthalic acid alkyl ester.

10. A light sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is a phenolic or a-naphtholic cyan dye-forming coupler.

11. A light sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is an open chain ketomethylene yellow dye-forming coupler.

12. A light sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is a S-pyrazolone magenta dye-forming coupler.

13. A light sensitive photographic silver halide emulsion having dispersed therein finely divided particles having at least one color photographic coupler and a permanent coupler solvent of the formulae R-R" are individually defined at each occurrence as a hydrogen atom or an alkyl group of one to eight carbon atoms; and R is a phenyl carbonyl group or an alkyl carbonyl group of two to 13 carbon atoms. 14. A light sensitive photographic silver halide emulsion having dispersed therein finely divided particles mulae on, (I111):

R'R" and R" are individually defined at'each occurrence as a hydrogen atom or an alkyl group of one to eight carbon atoms; and

n is an integer of 1-1000.

15. A light sensitive photographic silver halide emulsion having dispersed therein finely divided particles containing at least one photographic coupler and a permanent coupler solvent of the formula R is defined as an alkoxy carbonyl group of two to 15 carbon atoms.

16. A light sensitive photographic silver halide emulsion of claim 8 having dispersed therein finely divided particles containing at least one coupler compound and a permanent coupler solvent selected from the group consisting of pentaerythritol tetrabenzoate; 1,2,2,3- tetracarbethoxy propane; pentaerythritol tetralaurate; tris (2,2,4-trimethylpentyl)trimellitate; 1,2,4-benzenetricarboxylic acid, tris (Z-ethylhexyl) ester; 2,2,4- trimethyl-l,3-pentanediol isobutyrate, and a 2,2,4- trimethylpentanediol-1,3-adipic acid polyester terminated with isobutyric acid.

17. A light sensitive photographic silver halide emulsion of claim 8 wherein the solvent system contains 1- isopropyl-2,2-dimethyltrimethylenel ,3-diisobutyrate in a ratio of about 1 part by weight solvent-to-l part by weight coupler.

18. A light-sensitive photographic silver halide emulsion of claim 8 wherein the solvent system contains pentaerythritol tetrabenzoate in a ratio of about 1 part by weight solvent-to-1 part by weight couplers.

19. A color photographic element comprising a support and at least one light-sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing a coupler compound in a solvent system comprising at least one compound of the formulae R" and R"" are individually defined at each occurrence as a hydrogen atom or a lower alkyl group;

R is defined as an arylcarbonyl group or an alkylcarbonyl group;

R is defined as an alkoxy carbonyl group having up to 15 carbon atoms and n is an integer of 1-1000.

20. A color photographic element of claim 19 wherein the solvent system additionally contains a supplemental amount of a phthalic acid alkyl ester.

21. A color photographic element of claim 19 wherein the coupler compound is a phenolic-or a-naphtholic-cyan dye-forming coupler.

22. A color photographic element of claim 19 wherein the coupler compound is an open chain ketomethylene yellow dye-forming coupler.

23. A color photographic element of claim 19 wherein the coupler compound is a S-pyrazolone magenta dye-forming coupler.

24. A color photographic element comprising a support and at least one light sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing a coupler compound in a solvent system comprising at least one compound of the formulae R'-R" are individually defined at each occurrence as a hydrogen atom or an alkyl group of one to eight carbon atoms; and R" is a phenyl carbonyl group or an alkyl carbonyl group of two to 13 carbon atoms.

25. A color photographic element comprising a support and at least one light sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing a coupler compound in a solvent system comprising at least one compound of the formulae R is defined as an alkoxy carbonyl group of two to 15 carbon atoms.

27. A color photographic element comprising a support layer and at least one light sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing at least one coupler compound and a permanent coupler solvent selected from the group I CH I ilIl wherein R'R and R"" are individually defined at each occurrence as a hydrogen atom or an alkyl group of one, to eight carbon atoms; and

n is an integer of l-lOOO.

26. A color photographic element comprising a support and at least one light sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing a coupler compound in a solvent system comprising at least one compound of the formula consisting of pentaerythritol tetrabenzoate; l,2,2,3-

to-l part by weight coupler.

" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,779,765 Dated December 18, 1973 Inventor) Fred C. McCrossen and Harland J. Osborn It is certified the; error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lihe 22 (Formula B) "(R) should read (R5 RI Column 4, line 48 (Formula C), that part reading I- o v I 1 v R should read -C- Signed andse'aled this 23rd day of April 19714.. v

(SEAL) Attest:

EDWARD ILFLETC LER,JR. C, MARSHALL DANN Attesting fficer Commissionerof Patents 

2. A method of claim 1 wherein the solvent system additionally contains a supplemental amount of a phthalic acid alkyl ester.
 3. In a method for forming heat stable color photographic records obtained by exposing and developing a color photographic element containing one or more light sensitive silver halide emulsion layers having at least one photographic coupler, the improvement comprising utilizing as permanent coupler solvent at least one compound of the formulae
 4. In a method for forming heat stable color photographic records obtained by exposing and developing a color photographic element containing one or more light sensitive silver halide emulsion layers having at least one photographic coupler, the improvement comprising utilizing as permanent coupler solvent at least one compound of the formulae
 5. In a method for forming heat stable color photographic records obtained by exposing and developing a color photographic element containing one or more light sensitive silver halide emulsion layers having at least one photographic coupler, the improvement comprising utilizing as permanent coupler solvent at least one compound of the formula
 6. A method of claim 1 wherein the permanent coupler solvent is a member selected from the group consisting of pentaerythritol tetrabenzoate; 1,2,2,3-tetracarbethoxy propane; pentaerythritol tetralaurate; tris (2,2,4-trimethylpentyl) trimellitate; 1,2,4-benzenetricarboxylic acid, tris (2- ethylhexyl)ester; 2,2,4-trimethyl-1,3-pentanediol isobutyrate, and a 2,2,4-trimethylpentanediol-1,3-adipic acid polyester terminated with isobutyric acid.
 7. A method of claim 1 wherein the solvent system contains 1-isopropyl-2,2-dimethyltrimethylene-1,3-diisobutyrate in a ratio of about 1 part by weight solvent-to-1 part by weight coupler.
 8. A light sensitive photographic silver halide emulsion having dispersed therein finely divided particles containing at least one color photographic coupler compound in a solvent system comprising at least one compound of the formulae
 9. A light sensitive photographic silver halide emulsion of claim 8 wherein the solvent system additionally contains a supplemental amount of a phthalic acid alkyl ester.
 10. A light sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is a phenolic or Alpha -naphtholic cyan dye-forming coupler.
 11. A light sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is an open chain ketomethylene yellow dye-forming coupler.
 12. A light sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is a 5-pyrazolone magenta dye-forming coupler.
 13. A light sensitive photographic silver halide emulsion having dispersed therein finely divided particles having at least one color photographic coupler and a permanent coupler solvent of the formulae
 14. A light sensitive photographic silver halide emulsion having dispersed therein finely divided particles containing at least one color photographic coupler compound and a permanent coupler solvent of the formulae
 15. A light sensitive photographic silver halide emulsion having dispersed therein finely divided particles containing at least one photographic coupler and a permanent coupler solvent of the formula
 16. A light sensitive photographic silver halide emulsion of claim 8 having dispersed therein finely divided particles containing at least one coupler compound and a permanent coupler solvent selected from the group consisting of pentaerythritol tetrabenzoate; 1,2,2,3-tetracarbethoxy propane; pentaerythritol tetralaurate; tris (2,2,4-trimethylpentyl)trimellitate; 1,2,4-benzenetricarboxylic acid, tris (2-ethylhexyl) ester; 2,2,4-trimethyl-1,3-pentanediol isobutyrate, and a 2,2,4-trimethylpentanediol-1,3-adipic acid polyester terminated with isobutyric acid.
 17. A light sensitive photographic silver halide emulsion of claim 8 wherein the solvent system contains 1-isopropyl-2,2-dimethyltrimethylene-1,3-diisobutyrate in a ratio of about 1 part by weight solvent-to-1 part by weight coupler.
 18. A light-sensitive photographic silver halide emulsion of claim 8 wherein the solvent system contains pentaerythritol tetrabenzoate in a ratio of about 1 part by weight solvent-to-1 part by weight couplers.
 19. A color photographic element comprising a support and at least one light-sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing a coupler compound in a solvent system comprising at least one compound of the formulae
 20. A color photographic element of claim 19 wherein the solvent system additionally contains a supplemental amount of a phthalic acid alkyl ester.
 21. A color photographic element of claim 19 wherein the coupler compound is a phenolic-or Alpha -naphtholic-cyan dye-forming coupler.
 22. A color photographic element of claim 19 wherein the coupler compound is an open chain ketomethylene yellow dye-forming coupler.
 23. A color photographic element of claim 19 wherein the coupler compound is a 5-pyrazolone magenta dye-forming coupler.
 24. A color photographic element comprising a support and at least one light sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing a coupler compound in a solvent system comprising at least one compound of the formulae
 25. A color photographic element comprising a support and at least one light sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing a coupler compound in a solvent system comprising at least one compound of the formulae
 26. A color photographic element comprising a support and at least one light sensitive photographic silver halide emulsion layer applied thereto, Said emulsion layer having dispersed therein finely divided particles containing a coupler compound in a solvent system comprising at least one compound of the formula
 27. A color photographic element comprising a support layer and at least one light sensitive photographic silver halide emulsion layer applied thereto, said emulsion layer having dispersed therein finely divided particles containing at least one coupler compound and a permanent coupler solvent selected from the group consisting of pentaerythritol tetrabenzoate; 1,2,2,3-tetracarbethoxy propane; pentaerythritol tetralaurate; tris (2,2, 4-trimethylpentyl)trimellitate; 1,2,4-benzenetricarboxylic acid, tris (2-ethylhexyl)ester; 2,2,4-trimethyl-1,3-pentanediol isobutyrate; and a 2,2,4-trimethylpentanediol-1,3-adipic acid polyester terminated with isobutyric acid.
 28. A color photographic element of claim 18 wherein the solvent system contains 1-isopropyl-2,2-dimethyl-trimethylene-1,3-diisobutyrate in a ratio of about 1 part by weight solvent-to-1 part by weight coupler.
 29. A color photographic element of claim 18 wherein the solvent system contains pentaerythritol tetrabenzoate in a ratio of about 1 part by weight solvent-to-1 part by weight coupler. 